1. Field of the Invention
The present invention relates to a circuit breaker, and more particularly to a pry plate tripping circuit breaker.
2. Description of the Prior Art
A conventional circuit breaker comprises a housing to accommodate an operation mechanism, a lock catch, a tripping mechanism, a movable contact, an immovable contact, an arc extinguish chamber and a bimetallic strip. Two sides of the housing are provided with binding posts. One end of the bimetallic strip is connected to the binding post at one side of the housing. Another end of the bimetallic strip passes through a brush wire and is connected to the movable contact. The lock catch is hingedly disposed in the housing. The lock catch comprises a lock portion to mate with the operation mechanism and a temporary tripping portion to mate with the tripping mechanism. The tripping mechanism of the conventional mini circuit breaker adopts an electromagnetic tripping device. The coil of the electromagnetic tripping device is connected with the bimetallic strip. When the circuit breaker is in a normal state, the lock catch is biased by a return spring to hold the operation mechanism so that the movable contact and the immovable contact are connected. When a short circuit passes the bimetallic strip and the coil of the electromagnetic tripping device, the magnetic force generated by the coil overcomes the force of the spring to attract an armature to hit a drag rod. The drag rod brings the lock catch to turn by overcoming the action force of the return spring, such that the operation mechanism disengages from the lock catch. Finally, the movable contact is disconnected from the immovable contact to cut off the circuit. The tripping mechanism of the conventional mini circuit breaker adopts the electromagnetic tripping device which is disposed above the arc extinguish chamber. Because the electromagnetic tripping device is large in size and the conventional mini circuit breaker is limited to its entire volume, the size of arc extinguish chamber must be decreased. This limits the breaking capacity and rated current. The width of the housing of the conventional mini circuit breaker is 18 mm, and its rated current only has 63 A.
Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.